最近 ,笔者借辅导学生参加北京市第五届高中数学知识竞赛之机 ,有幸拜读了徐稼红先生编著的《中学数学应用与建模》一书 .该书中留有一些悬念 ,供读者思考回味 .在第六章第 1.4平面重心确定一节 ,有如下一例 :图 1确定如图 1所示的均匀梯形木板ABCD的重心位置 .书中提供了两种? Recently, the author used the guidance of students to participate in the fifth high school mathematics knowledge contest in Beijing. He was privileged to read the book “Application and Modeling of Middle School Mathematics” edited by Mr. Xu Jiahong. There are some suspense in this book for readers to ponder. In the section on the determination of the center of gravity of plane 1.4 in Chapter 6, there is an example as follows: Figure 1 Determine the position of the center of gravity of the uniform trapezoidal board ABCD shown in Figure 1.